Double cam drive

ABSTRACT

In a double cam drive incorporating a pair of cams arranged parallel to each other, the cams are geared to each other so that a rotating of the first cam in one direction effects rotation of the second cam in an opposite direction; means to be driven includes a follower which may alternately be disposed in the camming grooves of each cam, so that the disposition of the follower in the grooves of the first cam may effect a longitudinal shifting of the driven means in one direction, with a disposition of the follower in the camming grooves of the second cam causing a movement of the driven means in the opposite direction. This double cam drive may be used in conjunction with an inline machining device, whereby the driving means may comprise the transfer bar of said device, with its connected cam follower being arranged within the camming grooves of the first cam to effect the longitudinal shifting of said transfer bar and associated work supporting pallets in one direction, and then pivoting said transfer bar and its follower to effect a locating of said follower in the camming grooves of the second cam to provide for the movement of said transfer bar in an opposite direction.

United States Patent Fantz 1 Aug. 8, 1972 [541 DOUBLE CAM DRIVE [72] Inventor: Paul A. Fantz, St. Louis County,

[73] Assignee: UMC Industries, Inc.

[22] Filed: March 30, 1970 [21] Appl. No.: 23,543

[52] US. Cl ..'....74/58 [51] Int. Cl ..Fl6h 25/12 [58] Field of Search ..74/58, 57

[56] References Cited UNITED STATES PATENTS 1,712,717 5/1929 Rodrick ..74/58 2,472,919 6/1949 Paris ..74/58 3,347,478 10/1967 Stemberg ..74/58 Primary Examiner-William F. ODea Assistant Examiner-Wesley S. Ratliff, Jr. Attorney-Paul M. Denk [57] ABSTRACT In a double cam drive incorporating a pair. of cams arranged parallel to each other, the cams are geared to each other so that a rotating of the first cam in one direction effects rotation of the second cam in an opposite direction; means to be driven includes a foliowerwhich may alternately be disposed in the camming grooves of each cam, so that the disposition of the follower in the grooves of the first cam may effeet a longitudinal shifting of the driven means in one direction, with a disposition of the follower in the camming grooves of the second cam causing a movement of the driven means in the opposite direction. This double ca'rn drive may be used in conjunction with an inline machining device, whereby the driving means may comprise the transfer bar of said device, with its connected cam follower being arranged within the carnming grooves of the first cam to effect the longitudinal shifting of said transfer bar and associated work supporting pallets in one direction, and then pivoting said transfer bar and its follower to efiect a locating of said follower in the camming grooves of the second cam to provide for the movement of said transfer bar in an opposite direction.

4Claims,7DrawingFigures PATENTEDAus 8 m2 3.682.005 sum 1 or 4 FIG! INVENTOR PAUL A. FANTZ ATTORNEY PAIENTEDAUB 8191?.

SHEET 2 [If 4 INVENTOR PAUL A. FANTZ ATTOR NEY PATENTEDAut: elm 3,682,005

SHEET 3 OF 4 FIG. 3

FIG. 4 3/ INVENTOR 4 PAUL A. FANTZ.

ATTO R N EY FIG.5

PATENTEUAUB 8 m2 SHEET '4 0F 4 p 82 LL INVENTOR PAUL A. FANTZ BY QM ATTORNEY DOUBLE CAM DRIVE BACKGROUND OF THE INVENTION This invention relates generally to a drive mechanism, and more particularly, relates to a double cam drive which may urge a driven means alternately in a first direction and then in an opposite direction of movement.

Most drive mechanisms heretofore utilized in conjunction with various machining devices, for example, such as inline transferring devices furnishing automatic machining of various mechanical parts and components, generally include some form of a rack and pinion relationship whereby the turning of the pinion in one direction efiects a transfer or sequential movement of the various parts being machined along the machining device, with a rotation of said pinion in the opposite direction for effecting a retracting of the rack. Usually the rack is connected to or is integral with the transfer bar, and its shifting back and forth achieves repeated and successive movement of the components to be machined. For example, in US. Pat. No. 3,417,852, there is disclosed drive means comprising a rack and pinion relationship which is utilized to shift the transfer bars of a machining device in alternate and opposite directions, which is achieved simply through a rotation of the pinion in one direction, and then in an opposite direction. US. Pat. No. 3,062,353, shows a similar type work transfer mechanism which incorporates a rack and pinion relationship, in this particular instance, for use in moving work supporting pallets from one station to the next in a machine tool apparatus. Other type drive mechanisms, as for example, presently used in mechanical indexing of machine tools, have incorporated the use of worm gears for effecting a sequential movement of mechanical parts to preselect distances, although usually in one direction. This form of mechanical device is disclosed in US. Pat, No. 3,048,059. Present drive mechanisms for index tables or indexing apparatuses or the like have included the use of the single cam and its follower combination to achieve more perfection and precision in the sequential movement of components than can be achieved through the previously described worm gear type drive.

The foregoing type drive mechanisms, and in particular those drive mechanisms that are set up for urging the driven means into one direction and then into an opposite direction have a tendency, due to its double acting capacity, to become imprecise through wear in performing their driving function, a deficiency which cannot be tolerated especially in the precision machining operations that must be performed in the automatic machining apparatus. Usually, and in particular in those instances where the rack and pinion combination are utilized in effecting alternate movements in opposite directions of a transferring device, the exertion of force by the pinion and the rack in two opposite directions has a tendency to over strain the working of the combination which produces misalignment in machine settings, eventually to the extent that these components must be replaced.

For the foregoing reasons, a drive mechanism that may achieve movements of a driven means in opposite directions through usage of separately acting components that need only perform individual functions has a tendency to sustain the precision operation of the machining device in which the drive mechanism is incorporated, and thereby, sustain and prolong its working life.

One of the objects of this invention is to provide a double acting cam drive which may urge various components of a machining device or the like, into movement in various directions, each movement being regulated and controlled by a separate cam.

A further object of this invention is to provide a double cam drive that may be used in conjunction with an inline automatic machining device, one of said cams being utilized to shift longitudinally the transfer bar and work supporting frames, with the second of said cams acting to return said bar in preparation for the next shifting of the series of frames.

It is another object of this invention to provide a double cam drive which is substantially enclosed within a casing holding a quantity of lubricant which effectively continuously lubricates the entire drive mechanism.

Another object of this invention is to provide a double acting cam drive which has pivotally mounted thereto a tubular member that supports for longitudinal shifting the transfer bar of an inline machining device, which tubular member effectively pivots the bar and its associated cam follower in timed sequence to provide for the precision disposition of said follower within a select cam to achieve longitudinal shifting or retracting of said transfer bar.

It is yet a further object of this invention to provide the process of using a double acting cam drive which effectively shifts a driven means by operation of a cam in one direction, and then alternately returns said driven means through the use of a separate cam.

Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.

SUMMARY OF THE INVENTION In accordance with this invention, generally stated, the double acting cam drive is substantially engaged within a casing and housing that may be conveniently fixed within various of machining devices requiring alternate transfers of objects in first one direction and then in another direction. To achieve such, a pair of cams are arranged parallel and adjacent to each other, with each cam having integrally and peripherally formed helical camming grooves that are arranged substantially along the length of each cam, with said grooves being formed proximate either end of said cam into near circumferentially camming grooves that provide a significant amount of dwell time, or that amount of time which is required to allow for the reception of retracting of the follower that co-operates in combination alternately with each cam first to effect a shifting in one direction, and then a retraction in the opposite direction. Such drives may be effectively used in conjunction with many types of apparatuses that require achieved through the use of a double acting cam drive is that both cams of the drive, being intergeared together, are continually rotating each in their own direction of angular velocity, need not be reversed, and therefore have a lesser tendency to develop looseness or loss of tolerance due to a continual reversing of the direction of movement of a particular drive such as occurs in the use of prior art type drives. In this particular device, a follower is associated with the driven means, and said follower is disposed for reception within one of the cams, and more particularly within its camming grooves, so that the rotation of the cam will effect a shifting in one longitudinal direction of the driven means, and then by pivoting the follower into the adjacent cam, its camming grooves will effectively retract or reverse the direction of movement of the driven means. Following this, the follower once again can be shifted into the camming grooves of the first cam, and the entire cycle or strokes be repeated. Obviously, such a drive means, particularly in a device that requires the sequential shifting of various components automatically, is very beneficial from the standpoint of maintaining proper timing in the movement of the driven means, all achieved without having to reverse any mechanical movement in any component or cam of said drive.

When this double cam drive is used in conjunction with an inline machining device, a tubular member is pivotally mounted to the upward casing or housing of the drive, and a transfer bar is disposed slidably therein for movement in either direction that particular distance which is necessary to achieve the transfer of an associated pallet, its framework, and the mounted workpiece from one machining station to the next. A rack and pinion combination are operatively associated with the tubular member so as to achieve the timed pivot and transfer of the follower mounted to the transfer bar from one cam to the next to accomplish the precision and timed movement of said transfer bar alternately in opposite directions of movement.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,

FIG. 1 is a perspective view of the double cam drive with a portion of its casing being removed to dispose the inter-geared pair of cams;

FIG. 2 is a plan sectional view taken along the line 2--2 of FIG. 1, showing the parallel and adjacent relationship between the pair of cams;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1, showing the relationship of the pair of cams with its follower being disposed within the camming grooves of one cam as during operation;

FIG. 4 provides a back end view of the double cam drive showing the arrangement of the pinion segment integrally connecting to the tubular member and the rack which is energized to achieve pivotal movement of said tubular member and its slidably mounted transfer bar and follower;

FIG. 5 is a longitudinal sectional view taken along the line 5-5 of FIG. 1 showing the relationship of the right cam with respect to the transfer bar and its mounted cam follower;

FIG. 6 provides a top view in reverse of the tubular member and keyed transfer bar in the position undertaken for advancing pallets, as to the left; and

FIG. 7 provides a side view of the tubular member and transfer bar shown in FIG. 6, depicting the disposition of the cam follower extending through a slot in the tubular member.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings for one illustrative embodiment of the double cam drive of this invention,

in FIG. 1, reference numeral 1 generally depicts the invention showing the operative relationship of its various components, which comprise, generally, a housing 2 comprising side walls 3 and 4, with end walls 5 and 6 furnishing support for many of the structural components incorporated in this double cam drive. Inner walls 7 are provided inwardly of the said end walls, and along the length of the housing there are provided lateral supports, as at 7ain FIG. 2, which further reinforce the housing, and enhance the support of said drive. Arranged longitudinally within the housing 2, and more particularly being bearing mounted to its end or inner walls are a pair of barrel cams 8 and 9, which are arranged parallel and adjacent to each other, as shown in this view, although it is likely that this pair of cams could be arranged vertically one above the other, or at other angular relationships and still act effectively as a double cam drive.

The means for rotating the pair of cams of this invention comprise a standard motor 10 which includes in combination the usual means for controlling the speed and to achieve instantaneous stoppage of the rotation of the cams as is required during operation of the cam drive, andthis may be achieved through use of an electric or pneumatic clutch and brake combination as at 1 1, along with a standard speed reducer 12 which may effectively regulate the timed turning of at least one of the cams, cam 9 as here shown in the drawing. It is to be noted that one end of each cam is provided with an integral gear, such as gears 13 and 14, which respectively mount to cams 8 and 9, so that the rotation of cam 9 in one direction will cause a rotation of cam 8 in an opposite direction. Shown mounted to either the inner wall 7 or the end wall 6 of the housing is a rotary limit switch 15, which is effective for providing for the starting or discontinuance of the motor, clutch and brake combination after a predetermined number of turns have been made by the cams 8 and 9. The operation of this switch, and the number of turns to be made by the pair of inter-geared cams depend upon the longitudinal stroke of drive required from the cams, and which is required in the operation of the particular machine in which this double cam may be incorporated. Shown in a fragmentary view surrounding the pair of cams are the walls of a casing 16, which casing is disposed for holding an ample quantity of oil or other lubricant which is necessary to achieve proper and continuous operation of the cam drive, effectively lubricating all of its operative and mechanical components. Shown mounting to the structural housing 2, and either its end walls or inner walls are a pair of bearing mounts l7 and 18 which pivotally mount a tubular member 19 that has slidably longitudinally secured therein a driven member, such as a transfer bar 20 as may be utilized in conjunction with an inline automatic machining device as used in performing a plurality of machining functions along a series of work station. Also shown conporting a series of longitudinally shiftable pallets (not shown) from one work station to the next along such a device. When the double cam drive is utilized in this manner, the transfer bar 20 in cooperation with its tubular member 19 is effective in engaging select pallets for shifting them longitudinally along a path in the inline device sequentially from one work station to the next for performance thereat of a particular machining function.

The special relationship of the pair of cams 8 and 9 is more clearly shown in FIG. 2, wherein said cams are disclosed as being arranged parallel, and in proximate adjacency to each other, with their integral gears 13 and 14 being inter-geared to each other so that the revolving of one cam in one direction will effect a revolving of the adjacent cam at the same angular velocity in an opposite direction. Although, it is possible that these gears may be of different diameters so that the rotation of one cam may be at a speed greater than the speed of rotation of the other cam. Each cam is mounted at each end by bearings 21A, in this particular instance, being tapered needle bearings, although other forms of bearings may operate just as effectively.

An example of an effective design in this double cam drive may be described by analyzing FIG. 2, wherein the motor may comprise the standard AC. or DC. electric motor that may produce a sustained drive of 1800 r.p.m.s. This motor is geared to an air or electric clutch and brake combination, at 11, so that the motor torque may be discontinued instantaneously, or recommenced, depending upon the required timed operation of the pair of cams. A standard speed reducer 12, for example one reducing the motor speed at a ratio of :1, may be effective in converting the motor torque to a reduced speed in turning the worm gear 22 to achieve rotation of the cam 9. Obviously, any rotation of cam 9 will effect an opposite rotation of cam 8. The

rotary limit switch 15 is operatively associated with the end of the cam 8, opposite its geared end 13, and such a rotary limit switch may be effective in controlling the number of revolutions of the cams, so that, for example, when cam 8 may make two rotations or around 600, said switch 15 may immediately instruct the clutch and brake unit to cease rotation of the cam 9. Obviously, additional timing mechanisms (not shown) may initiate a timed delay in the operation of the cam drive as when a machining operation is to be performed upon the inline transfer machine, and may then once again instruct the clutch and brake unit to allow further rotation of the motor and revolving of the pair of cams. Furthermore, this illustration by way of example of the capacity of the various motor, clutch, brake, and speed reducer combinations is set forth by way of example, and in the event that a larger or smaller double cam drive is required to perform a particular operation, these capacities may be varied so as to provide the most efficient relationship of components required to operate the pair of cams.

In FIG. 2, the arrangement of the various camming grooves 23 and 24 as integrally fonned within and around the periphery of the pair of cams 8 and 9, respectively, are more fully depicted. Preferably, these camming grooves are formed as helical grooves surrounding approximately the length of each cam, and since it is desirable to utilize the longitudinal push or pull force of the cam to urge the driven means, or transfer bar 20, alternately forward and then rearwardly, said camming grooves are here shown arranged at approximately a 30 to 35 angle with respect to the diameter of the cam. At this angular relationship, the camming grooves have a tendency to longitudinally push or pull the driven means, rather than urge its movements by means of any significant torque force such as occurs when the camming grooves are arranged at angles substantially above 45. Although, it is likely that the camming grooves may be maintained at angles above 45 in the event that it is desired to lengthen the stroke of the driven means with a minimum amount of camming grooves. The camming grooves proximate either end of each cam are turned and arranged substantially circumferentially of the cam, being arranged somewhat at a normal to the longitudinal axis of each cam, so that as the cam follower of the driven means is being received or removed from the grooves 'of the cams, a certain period of dwell time will be provided to allow for this change over, and to further provide some tolerance in the event that there is any overrun in the rotation of the cams before the follower may be removed or inserted with respect to the same. In this particular embodiment, the design of the dwell time is approximately angular degrees, or approximately one-third the circumference of the cam, although this dwell time may be increased up to approximately 300 more or less, depending upon the length of time required to provide for reception or removal of the follower from the camming grooves. In this particular double cam drive, the follower of the driven means is initially received within the dwell groove 25 and then is eventually urged forwardly as the follower enters into the camming groove 24 and until it reaches the forwardmost extentof its stroke, or enters into the dwell groove 26, at which time the follower, as will be hereinafter described, is pivoted into the dwell groove 27 of the cam 8, and then urged rearwardly by operation of the camming grooves 23, until such time as the follower enters into the dwell groove 28. At this time, the follower is once again pivoted back to its initial position, and enters into the dwell groove 25 in preparation for the next stroke of the double cam drive. Usually this process could be accomplished, and the stroke of the double cam drive be run continuously to the timed operation of the pivoting of a follower from one cam to the next, as through the continuous rotation of the cams 8 and 9, and the urging of the follower by the end of each dwell groove into the dwell groove of the adjacent cam. On the other hand, it is likely that some delay will be necessitated either initially or during the stroke of the cam drive, and therefore, the rotary limit switch 15 may be timed to instantaneously cease rotation of the cams for a select period of time so that a particular machining operation may be performed by .the apparatus in which this double cam drive is incorporated.

By referring to FIG. 3, it can be seen that a cam follower 29 is rotatably secured by means of a mount 30 to the transfer bar 20 of this device. Needle bearings have been found useful in securing the follower to its mount. As here shown, the cam follower is angularly fixed for cooperating with the camming grooves 24 of F cam 9, as when said follower and driven means is being urged forwardly by operation or rotation of said cam, but that upon the return stroke of the driven means, the follower will be pivoted approximately 75 to the right, and become radially disposed with respect to cam 8, being arranged for cooperating with its camming grooves 23 for retracting of said follower and its attached transfer bar. Obviously, the degree of angular pivoting of the follower from one cam to the other will depend upon the size and proximity of the relationship of cam 8 to cam 9, and in the event that said cams may be larger or smaller in size, or the driven means be raised or lowered with respect to the earns, the amount of angular pivoting of said follower will vary accordingly. By referring to FIG. 4, the means for pivoting the transfer bar 20, its follower, and the tubular member 19 supporting said bar, is shown. This pivoting means may undertake the form of a rack and pinion relationship associated with the inner wall 7, wherein pinion segment gears 31 are formed integrally around a portion of the tubular member 19, and said gears are disposed for engagement with the teeth of a rack 32, which is disposed for timed lateral displacement by means of a cylinder 33. When the rack 32 is retracted toward the cylinder 33, the follower will be caused to pivot for reception within the camming grooves of cam 9, but when the rack 32 is projected outwardly from the cylinder 33, the follower will be angularly pivoted for removal from said cam 9 and its reception into the camming grooves of cam 8. At each end of rack movement, the pinion segment will abut the bottom surface 18A of bearing mounts or caps 18 providing a positive stop to the angular pivot of tube 19 and follower 29. This abutment provides a positive resistance to any torque imposed on the tube 19 by the cam and follower. Limit switches 34 and 35 are disposed for cooperating with stops 36 and 37 adjustably secured to the threaded end 38 of rack 32, to insure the required angular position of the tube 19 and the follower 29 before the clutch can be engaged and rotation of the cams started. In operation, this rack and pinion combination, and the cylinder 33, is timed for sequential operation with respect to the disposition of the cam follower 29 in either of the dwell grooves 25 through 28, so that when it is required to effect a reception or removal of the follower from either of the cams, during these particular instances of dwell, the cylinder will become energized. Actually, the cylinder will be timed for operation in conjunction with the other timing components of this drive, including the operation of the rotary limit switch 15, and the functioning of the clutch-brake unit 21.

By referring to FIG. 5, the cam follower 29 is shown rotatably mounted to its mount 30, which is rigidly secured to the transfer bar 20 by means of a pair of fasteners 38. Also shown in this particular drawing is the relationship of the rack 32 which engages with the pinion 31 of tubular member 19. To facilitate the lateral shifting of the rack 32, a series of needle bearings 39 support said rack.

The lubricant holding casing 16 is more clearly shown in FIG. 3, and is herein illustrated as enveloping substantially most of the exposure of the pair of cams, and is provided with an oil filler duct 40, with a lubricant overflow duct 41 maintaining the desired level of oil within the casing 16. An oil drain 42 is provided as when it is necessary to drain all of the lubricant from the drive. At that location where the casing 16 comes into proximity with the sides of the tubular member 19, a pair of seals are mounted upon the casing and are sealingly biased against the outer surface along the length of said tubular member above said casing so as to prevent the entrance of any dirt, or machine tool cutting fluid into the interior of said casing, and intermixing with the lubricant retained therein. This sealing relationship is necessitated since the tubular member 19, along with its associated follower and transfer bar 20 are repeatedly pivoted to achieve the locating of the follower 29 within the grooves of the pair of cams 8 and 9 By referring once again to FIG. 5, the relationship of the transfer bar 20 as slidingly engaged within the tubular member 19 can be seen. The bearings 17 and 18, and their fastened bearing caps, secure the tubular member in place for pivotal movement, and a stop 44 fixes the pinion 31 with respect to the bearings 17, so as to prevent any longitudinal shifting of the tubular member 19. By referring to FIG. 6, it can be seen that the transfer bar of most inline automatic machining devices is segmented, as at 20 and 20A, being held together by means of a pin 45. By referring also to FIG. 7, a longitudinal slot 46 is provided through a substantial length of the tubular member 19, so that the follower 29, and its mount 30, as connected to the transfer bar 20, are free for limited longitudinal shifting as the follower 29 is urged forwardly or rearwardly by operation and its association within the grooves of cams 8 and 9. Another longitudinal slot, as at 47 is provided along the length of the tubular member 19, and a series of keys as at 48, are rigidly fastened at predetermined intervals along the length of the transfer bar 20. Intermediate each key there is provided a slot or space as at 49, and said spaces are provided for engagement with any form of a detent, finger, or the like, as it 49a, which may depend from the pallets 49b or other work supporting plates that are to be shifted along the rails 21 of the inline machining device. As shown, when the follower 29 is disposed within the forwardly moving cam 9, these keys 48 will be disposed upright for engagement with the underside of a pallet, but when the follower 29 is pivoted for disposition within the cam 8, the keys 48 will be canted to the side, free from engagement with the pallets, to be returned along with the transfer bar 20 for initiation of a new stroke of the cam drive. To provide clearance for any pallets that may be disposed above the tubular member 19 as the transfer bar 20 is being retracted, a pair of slots, as at 50, are provided within said tubular member, and spaced apart at a distance approximating the length of the stroke of the cam drive, so that as the transfer bar is retracted in preparation for its next stroke, the pallets resting above the slots 50 will be picked up by the next succeeding slots 49 of the transfer bar. After the bar is retracted by means of the operation of cam 8 and once again pivoted, the pallets engaged within the slots 50 will be picked up by the associated slots 49. Then, as the follower is engaged within the cam 9, and urged forward, the various slots 49 of the transfer bar as engaging the following pallets will urge them forward each to the next succeeding work station approximating one stroke of the cam 9.

In FIG. 5, gaskets or seals 51 are provided proximately each end of the tubular member 19 surrounding the transfer bar 20 so as to prevent the entrance of any deleterious particles therein.

Numerous variations in the construction of the double cam drive of this invention, within the scope of the appended claims will occur to those skilled in the art in the light of the foregoing disclosure. For example, another may attempt to insert an intermediate gear between the gears 13 and 14, and acquire a rotation of the cams 8 and 9 in the same direction. In view of this, and by rearranging through machining the camming grooves in each of said cams, i.e., by forming the camming grooves in one cam opposite to the camming grooves in the adjacent cam, this double cam drive can be made to operate and achieve the same results of the described embodiment. The discussed embodiment is merely illustrative, and any modification or changes in the structure or function of this drive that are equivalent to those described herein, and encompassed by the claims, are intended to be within the scope of any patent protection issuing thereon.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

l. A double cam drive comprising a pair of cams arranged parallel and adjacent to each other, said cams being inter-geared whereby the rotation of the first cam effects the rotation of the second cam, drive means operatively associated with at least one of said cams to cause said rotation, said cams having camming grooves which are arranged substantially around their periphery, means to be driven including a transfer bar, a follower connecting to said driven means and arranged for alternate reception in the camming grooves of each of said cams whereby the disposition of said follower in the camming grooves of said first cam causes said driven means to be moved a stroke in one direction, the disposition of said follower in the camming grooves of said second cam effects a movement of said driven means for a stroke in the opposite direction, means pivotally mounting said transfer bar to said device, said means comprising a tubular member slidably retaining a portion of said transfer bar therethrough, bearings pivotally mounting said tubular member to the machining device, said tubular member having a longitudinal slot disposed therethrough for projection of the follower, a rack and pinion means operatively associating said tubular member with the machining device, whereby the timed operation of said rack efl'ects a shifting of said follower from its engagement with the one cam to the other cam.

2. The invention of claim 13 wherein said tubular member is provided with a second longitudinal slot disposed therethrough, said transfer bar provided with at least one key disposed within said slot to effect pivoting of said transfer bar simultaneously with the pivoting of said tubular member, said keyed tranfer bar disposed for longitudinally shifting within said tubular member alternately in one direction and then in the opposite direction as said follower is urged in one direction by said first cam and then in the opposite direction by the gi 'fil invention of claim 2 wherein said inline machining device is of the type incorporating a series of pallets each for holding a fixture for supporting a workpiece, a key of said transfer bar disposed for engagement with one of said pallets for driving it in one direction as the follower is urged forward by the first cam, said key being disengaged from said pallet as said follower is moved in the opposite direction by the operation of the other cam.

4. A double cam drive comprising a pair of cams arranged parallel and adjacent to each other, said cams being inter-geared whereby the rotation of the first cam effects the rotation of the second cam, drive means operatively associated with at least one of said cams to cause said rotation, said cams having camming grooves which are arranged substantially around their periphery, means to be driven, a follower connected to said driven means and being arranged for alternate reception in the camming grooves of each of said cams whereby the disposition of said follower in the camming grooves of said first cam causes said driven means to be moved a stroke in one direction, the disposition of said follower in the camming grooves of said second cam effects a movement of said driven means for a stroke in the opposite direction, a casing substantially surrounding said pair of cams, said casing disposed for retaining a supply of lubricant for lubricating said cams and follower during the operation of the device, and seals connecting to said casing and being maintained in contiguity with said driven means to prevent access at this location into the casing.

; I J NI FE' I; PATENT O FFICE CERTIFICATE OF CORRECTION P a teric-'No.; 3682 5 Dated August 8 1972 Inventor(s) Paul A. Fant z If is certified that error" appears in the -above-idemtified patent end that said- Letters Patent are hereby corrected as shown below:

Column 10, line 6,' delete "Claim l3" andinsert therein "Claim'l".

Signed elud s angled this 9th day of J anuaryv1973.

(SEAL) Attest: I EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Pateni F ORM P04 050 (10-69) USCOMM-DC 50375-P69 U.S4 GOVERNMENT PR'NYING OFFICE: I969 0-366-334 

1. A double cam drive comprising a pair of cams arranged parallel and adjacent to each other, said cams being inter-geared whereby the rotation of the first cam effects the rotation of the second cam, drive means operatively associated with at least one of said cams to cause said rotation, said cams having camming grooves which are arranged substantially around their periphery, means to be driven including a transfer bar, a follower connecting to said driven means and arranged for alternate reception in the camming grooves of each of said cams whereby the disposition of said follower in the camming grooves of said first cam causes said driven means to be moved a stroke in one direction, the disposition of said follower in the camming grooves of said second cam effects a movement of said driven means for a stroke in the opposite direction, means pivotally mounting said transfer bar to said device, said means comprising a tubular member slidably retaining a portion of said transfer bar therethrough, bearings pivotally mounting said tubular member to the machining device, said tubular member having a longitudinal slot disposed therethrough for projection of the follower, a rack and pinion means operatively associating said tubular member with the machining device, whereby the timed operation of said rack effects a shifting of said follower from its engagement with the one cam to the other cam.
 2. The invention of claim 13 wherein said tubular member is provided with a second longitudinal slot disposed therethrough, said transfer bar provided with at least one key disposed within said slot to effect pivoting of said transfer bar simultaneously with the pivoting of said tubular member, said keyed tranfer bar disposed for longitudinally shifting within said tubular member alternately in one direction and then in the opposite direCtion as said follower is urged in one direction by said first cam and then in the opposite direction by the other cam.
 3. The invention of claim 2 wherein said inline machining device is of the type incorporating a series of pallets each for holding a fixture for supporting a workpiece, a key of said transfer bar disposed for engagement with one of said pallets for driving it in one direction as the follower is urged forward by the first cam, said key being disengaged from said pallet as said follower is moved in the opposite direction by the operation of the other cam.
 4. A double cam drive comprising a pair of cams arranged parallel and adjacent to each other, said cams being inter-geared whereby the rotation of the first cam effects the rotation of the second cam, drive means operatively associated with at least one of said cams to cause said rotation, said cams having camming grooves which are arranged substantially around their periphery, means to be driven, a follower connected to said driven means and being arranged for alternate reception in the camming grooves of each of said cams whereby the disposition of said follower in the camming grooves of said first cam causes said driven means to be moved a stroke in one direction, the disposition of said follower in the camming grooves of said second cam effects a movement of said driven means for a stroke in the opposite direction, a casing substantially surrounding said pair of cams, said casing disposed for retaining a supply of lubricant for lubricating said cams and follower during the operation of the device, and seals connecting to said casing and being maintained in contiguity with said driven means to prevent access at this location into the casing. 